v2.0.3

New features:

• All messages created with create() now have a symbol property MESSAGE_TYPE
  that provides access to the messages type. Use containsMessageType(yourMessage)
  to check if a message contains its type and access it with yourMessage[MESSAGE_TYPE].

  Note that this is an experimental feature - it is here to stay, but implementation
  details may change without notice.

  Many thanks to @odashevskii-plaid for the contribution.

Bug fixes:

• Generated create() method for speed optimized code got left behind in #55
  Thanks to @odashevskii-plaid for the find!

• Infinite recursion on compile step when using custom option on message used as custom option #141
  Thanks to @doochik for bringing it up.